Toimela and Tähti studied the effect of HgCl2 on cultured retinal pigment epithelial cells from pig and from a human cell line. They observed that 0.1 mM mercury reduced glutamate uptake by some 25 per cent. They interpreted this effect as due to inhibition of protein kinase C (PKC).

The retina of the eye accumulates mercury when there is exposure to mercury vapour. Mercury remains in the retina for a very long time -- often for years. Accumulation of mercury is seen, in monkeys, in the inner portion of the retina, in pigment epithelial cells and capillary walls (Warfvinge and Bruun 2000).

Squirrel monkeys were exposed to mercury vapour at different concentrations and for different numbers of days. The calculated total mercury absorption ranged between 1.4-2.9 mg (range of daily absorption 0.02-0.04 mg). The monkeys were killed at different intervals after the end of exposure (range 1 month - 3 years) and the eyes were enucleated. Mapping of the mercury distribution in the eye revealed that the non-myelin-containing portion of the optic disc was densely loaded with mercury deposits, which are mostly confined to the capillary walls and the glial columns. The pigmented epithelium of the pars plicata of the ciliary body and of the retina contained a considerable amount of mercury. In addition, the retinal capillary walls were densely loaded with mercury deposits, even 3 years after exposure. It was also found that the inner layers of the retina accumulated mercury during a 3-year period. It is known that the biological half-time of mercury in the brain may exceed years. This seems also to be the case for the ocular tissue.

Subclinical colour vision loss, mainly in the blue-yellow range, was observed in the workers. This effect was related to exposure, as indicated by the correlation between HgU and CCI (r=0.488, P<0.001).

The effect of inorganic mercury on the integrity of the endothelium of isolated bullfrog (Rana catesbeiana) corneas was examined by spectrophotometric analysis of corneal uptake of the vital stain Janus green, and by both transmission (TEM) and scanning (SEM) electron microscopy.